The present invention relates to image processing apparatuses and methods for converting, for example, the frame rate of an inputted image signal by frame interpolation, and in particular, relates to a technique for excellently performing frame interpolation to an image containing an image portion having transparency.
The smoothing of the movement of an image by the so-called frame interpolation where an interpolation frame is inserted between a sequence of frames of an input image signal is currently widely performed. Such image processing is called, for example, frame rate conversion, where the number of frames (frame frequency) of an inputted image signal is converted by inserting the above-described interpolation frame between a sequence of frames of the input image signal.
In such frame rate conversion, an interpolation frame is generated by detecting a motion vector indicative of a movement of an object within an image from two consecutive frames within the inputted image signal and then calculating an average or median value between values (data) of a pixel or block of the two frames indicated by the motion vector. Generally, this motion vector is detected using a block matching method, for example.
This motion vector is also used in encoding an image, and the encoding of an image is performed individually after separating the background image and an object in the image. At this time, when an object has transparency, a transparent image and the background image may be identified and separated from each other using a plane data indicative of the transparency thereof, so that each may be encoded individually. Such prior art is known in JP-A-2000-324501, for example.